2021 KTM 450 SX-F

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Bike Test: 2021 KTM 450 SX-F Review

Tester: Chris Seibenhaar
Height: 5'10"
Weight: 180 lb
Age: 35
Class: Intermediate

The model year 2021 will be one of refinement for the KTM 450SX-F, with minor updates throughout the bike that focus on performance or reliability. Keep in mind, that’s not KTM just sitting back and relaxing. Rather the 2020 model was a banger of a machine, after all, it was second in the shootout last year with some riders making it their number one pick.

The list of changes have already been posted for months now, so here’s the cliff-notes; new features and settings in the air fork, shock changes to reduce fading and new seals to reduce friction, Geomax MX33 tires, new map settings to further differentiate between map 1 & 2, and a host of motor updates for increased reliability. 

While other manufactures have all abandoned their air fork hopes, KTM continues to plug away, refining them year after year. In the past I felt like the WP air forks gave you two options 1) a plush feel over chop and into corners 2) hold up charging into jump faces or landing into braking bumps. But no way were you going to get both. For 2021 the 450SX-F has new fork internals which feature an enlarged air and oil bypass to reduce pressure peaks, a new mid-valve damping system, and a smaller rebound spacer in the air leg to allow for a more linear feel, and a stiffer setting front and rear to tie it all together. So, what does that mean? 

With the new fork design, I found myself able to run a higher air pressure than I’ve ever ran on WP air forks (11.1 bar) and still getting a great feeling out of the fork, both with how the bike rode and also my confidence in the front end. It’s hard to tell which of the new fork features attribute to this feeling, but the usual air pressure spikes that come with high bar/psi were not there. The fork has a very progressive and linear feel to it, far more than any previous year.  By the day’s end, I was able to get the forks to holdup when needed (jump face transitions and landing into braking bumps) but still get the bike to track over braking bumps and easily turn into corners with very little effort. Additionally, I felt the stiffer settings in the fork help keep the higher pressure that I was running under control by maintaining stroke speed, both on compression and rebound. For the shock, after a few changes to high and low speed compression, it seemed like I had to try and brake rear end traction. Correction, I had to try harder than trying. In some corners (especially in MAP 2 + TC) the bike would have a bit of a slide, but that was it. All it wanted to do was shoot out of the corner floating the front wheel. 

Mapping was also changed for 2021 with the effort of making the differences between the two maps more discernable. MAP 1 + TC is like a “soft-standard” map, MAP 1 is the “standard” map, MAP 2 + TC is like a “soft-aggressive” map, and MAP 2 is a hard hitter. For Perris Raceway with tight 180-degree corners, a mix of tacky corner exits and dusty marbly mid-corners, I found MAP 2 (no TC) a bit aggressive at the initial crack of the throttle, more so later in a moto. Mainly it was the transition off throttle in the 0-5% range, if not extremely precise with the throttle, the bike would lunge and throw off my rhythm mid-corner. I did find MAP 2 + TC to be a good all-around map throughout the day, kept me feeling spicy without being so reactive to my mistakes. 

These were the most noticeable changes made from 2020 to 2021, the remainder of the changes focused on internal reliability which, from my recollection of the 2020 bike, I could not feel any difference…and that is a good thing. I really liked the 2020 powerplant, I would have hated to see any changes that made a negative impact on this engine. 

Specifications

Product KTM 450 SX-F
Model Year 2021
Engine Size 450cc
Engine Type Four-Stroke
Engine Displacement 449.9 cm³
Bore x Stroke 95 x 63.4mm
Compression Ratio 12.75:1
Fuel System Keihin EFI w/ 44mm throttle body
Ignition Electric starter
Transmission 5-speed
Final Drive 5/8” x ¼” chain
Suspension Front WP XACT-USD, Ø 48 mm
Suspension Rear WP XACT Monoshock with linkage
Brakes Front 260 mm Disc brake
Brakes Rear 220 mm Disc brake
Tires Front Dunlop Geomax MX33
Tires Rear Dunlop Geomax MX33
Overall Length
Overall Width
Overall Height
Seat Height 37.4 degrees
Wheelbase
Ground Clearance 14.6 inches
Rake/Trail
Fuel Capacity 1.85 gallons
Curb Weight 234 pounds
Features
Miscellaneous
Price $10,199
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